The present invention relates to a device an a method for the excitation and/or damping and/or detection of vibrations of a plate-shaped device using a piezoelectric strip device.
Although it may be applied to any system, the present invention and the fundamental problems it addresses will be explained with reference to systems that include a glass plate or a plastic plate or a printed circuit board as the plate-shaped device.
The older German patent application DE 10 2007 012 925 describes a method and a device for damping structural vibrations of a carrier device using a piezoelectric actuator device. The piezoelectric actuator device includes a strip, which may be piezoelectrically excited to generate longitudinal and/or transverse vibrations that dampen the structural vibrations, that includes a first end region and a second end region, and that is connected at least at either the first end region or a second end region to a surface of the carrier device in such a manner that the longitudinal and/or transverse vibrations may be transmitted to the carrier device. The dimensions of the strip are therefore substantially smaller than those of the carrier device, and so the vibrations are transmitted in a substantially punctiform manner.
FIG. 13 shows a device for damping structural vibrations of a carrier device using a piezoelectric actuator device according to the older German patent application DE 10 2007 012 925.
In FIG. 13, a carrier device is labeled using reference numeral 1. A piezoelectric actuator device in the form of a strip 2, which is piezoelectrically excitable to generate longitudinal and/or transverse vibrations that damp the structural vibrations, is installed on surface OF of carrier device 1. Strip 2 includes a first end region E1 and a second end region E2. First end region E1 is connected via bonding in region 3a to surface OF of the carrier device, and second end region E2 is connected via bonding in region 3b to surface OF of carrier device 1. The connection of strip 2 to surface OF is not limited to the strip-shaped bonding that is shown, however.
Strip 2 extends such that it arches above surface OF, thereby spanning a cavity 6 in the manner of a bridge. An additional mass device 5 is installed in the middle of the side of strip 2 that faces away from surface OF. The purpose of mass device 5 is to produce a reaction force to dampen the structural vibrations. Strip 2 is multilayered in design. In the middle thereof, a piezoelectric ceramic layer 20 is located, which may be electrically activated using electrode layers 21 which are adjacent thereto. An epoxy resin layer 21 and a polyimide layer 22 are located on and under the electrode layers. Electrode layers 21 are electrically connected via a connection device, which is not depicted, in order to couple the vibrations, which extend in the longitudinal and/or transverse direction of strip 2, into strip 2.
If only longitudinal vibrations are coupled into piezoelectrically excitable strip 2, as in the present example, this results—due to the geometric configuration—in a vibration mode S1, in which mass device 5 is deflected downwardly and upwardly, perpendicular to surface OF along the double arrow shown in FIG. 13.
Although this is not shown in the figure, strip 2 has a substantially smaller extension than carrier device 1, e.g., the size of strip 2 is in the range of 1-2 cm long×0.5 cm wide, and the size of carrier device 1 is in the range of 10-20 cm long×5-10 cm wide.